Portable air compressor/tank device

ABSTRACT

A portable, low cost air supply device for accumulating and dispensing compressed air converted from photovoltaic energy. The device includes one or more photovoltaic cells, a capacitor, an electronic trigger device, a solenoid, a valve manifold, a reservoir, and a device for dispensing accumulated air. The photovoltaic cell(s) charge the small, low cost capacitor. When saturated, the capacitor is triggered by a solid-state device to discharge the electrical charge to a solenoid. The energized solenoid then extends its plunger into a hole in the valve manifold, compressing air into the manifold. The compressed air moves past a check valve, and into a storage reservoir. The solenoid rapidly de-energizes, the plunger retracts, and the solenoid is now ready for another compression stroke.

[0001] This application claims the benefits of provisional applicationSerial No. 60/426,294 filed Nov. 14, 2002.

FILED OF THE INVENTION

[0002] The invention relates to a portable, low cost air supply devicefor accumulating and dispensing compressed air and powered byphotovoltaic energy.

BACKGROUND OF THE INVENTION

[0003] U.S. Pat. No. 6,367,259 describes an air compressor system thatincludes a rotary induction motor, motor control circuitry, expensivelarge capacitors, and associated packaging. To date, air compressorsystems that accumulate energy from photovoltaics have been made up ofconglomerations of large static devices, working together andcoordinated by complicated control circuitry and sensors. These systemsare commonly formatted as banks of batteries or banks of large expensivecapacitors. Such storage devices drive induction motors, which thenfinally drive compressors.

SUMMARY OF THE INVENTION

[0004] An embodiment of the invention provides an air supply device andmethod that accumulate and distribute compressed air without the use ofthe large static devices referenced above, that can be hand carried tothe point of use with a size scale easily applied by the end user, andthat eliminates the need for a rotary induction motor, motor controlcircuitry, expensive large capacitors, and associated packaging.

[0005] One illustrative embodiment of the invention involves aself-replenishing, portable air supply device that includes an airreservoir tank and one or more photovoltaic cells disposed exterior ofthe air reservoir tank. The photovoltaic cell(s) provide(s) electricalpower to a capacitor, which intermittently discharges to a solenoid,which then mechanically compresses air into the reservoir tank. In apreferred embodiment of the invention, the capacitor and solenoid andother related components are located inside the air reservoir tank.

[0006] The invention optionally provides on the air reservoir tank oneor more of a flashlight, a self-retracting hose reel, a hose pressureindicating gauge/LCD readout, a manually activated valve to dispensecompressed air, and a connector to secure the portable reservoir tank ina location of use (i.e. pick-up truck bed). The invention also envisionsoptionally providing one or more remote-mounted photovoltaic cell(s) toallow the air supply device to serve as an imbedded power unit within alarger system.

[0007] The invention is advantageous to improve the manufacturabilityand affordability of a portable air compressor system by virtue ofreduced number of component parts, simplified integral packaging(placing sensitive components inside the air reservoir tank), andenabling the use of a very small, and exponentially cheaper capacitor.Other advantages of the invention will become more readily apparent fromthe following description taken with the following drawings.

DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a schematic view of an air supply device pursuant to anembodiment of the invention shown for use in inflating a pick-up trucktire.

[0009]FIG. 2 is a perspective view of an air supply device to anembodiment of the invention with the air reservoir tank partially brokenaway to show the portion of the solenoid pump assembly residing insidethe tank.

[0010]FIG. 2A is an enlarged view of the solenoid pump assembly.

[0011]FIG. 3 is a sectional view of the solenoid pump assembly and airreservoir tank wall, depicting the pneumatic circuit. The circuit boardB and capacitor and trigger device thereon are shown schematically forconvenience.

[0012]FIG. 4 is a schematic view showing the photovoltaic cells andrelated electronic components relative to the air reservoir tank,depicting the electrical circuit.

[0013]FIG. 4A is an enlarged view of the electrical trigger device ofFIG. 4.

[0014]FIG. 5 is a perspective view of the air supply device showing theair reservoir tank having thereon a flashlight, a self-retracting hosereel, a hose pressure indicating gauge/LCD readout, a manually activatedvalve to dispense compressed air, and a locking lug to secure theportable reservoir tank in locations of use (i.e. pick-up truck bed).

[0015]FIG. 6 is a perspective view showing the air supply device havinga lug for mounting the air supply device on the bed of pick-up truck.

[0016]FIG. 7 is an elevational view of the air supply device having amanual trigger thereon actuated to dispense compressed air from the airreservoir tank.

[0017]FIG. 7A is an enlarged view of the manual trigger.

DESCRIPTION OF THE INVENTION

[0018] Referring to FIG. 1, an air supply device and method pursuant toan illustrative embodiment of the invention comprises an air reservoirtank 1 of conventional fabrication (mild steel, or aluminum, or plasticcomposite construction) with an integral carry handle 21 and attachedsupporting feet 20 for resting on a horizontal surface. A pipe nipple 2,FIG. 2 is disposed on and extends through and into the air reservoirtank 1. A solenoid pump assembly 19 is configured as a plug received inthe pipe nipple 2, with certain mechanical and electrical circuitry ofthe solenoid pump assembly disposed in, and totally enclosed within, theair reservoir tank 1 as will become apparent below.

[0019] On the exterior surface of tank 1 is/are mounted one or morephotovoltaic cell(s) 14. The energy from the photovoltaic cell(s) 14 isused to charge intermittently solenoid 8 of the solenoid pump assembly19 using an electrical circuit shown in FIG. 4. Solenoid 8 and itsenclosed plunger 7 reside in the tank 1, FIG. 3, and are configured tofunction as an air compressor pump when combined with valve manifold 11.The solenoid 8 includes a housing with a threaded or flanged end that isthreaded or bolted onto the valve manifold 11 to join them together asshown in FIG. 3. The combination of the solenoid 8 and valve manifold 11is referred to as the solenoid pump assembly 19. On it's retract stroke,plunger 7, functioning as a piston, draws atmospheric air through theexternally protruding tank valve 3 of the solenoid pump assembly 19.Once the solenoid 8 is energized, plunger 7 advances, compressing airpast spring-biased check valve 13 and into the air reservoir tank 1. Thesolenoid 8 can be a commercially available solenoid, such as Ledex brandsize 3EC model available from Saia-Burgess, Inc.

[0020] The valve manifold 11 has attached, or built integral to it,devices including 1) a pressure relief valve 6, to prevent tank 1 overpressurization; and 2) a Schrader style tank valve 3, functioning as anair intake, back flow check valve, and allowing the filling of tank 1from an external compressed air source. Further devices attached orbuilt integral to manifold block 11 include gauge port 5 for mounting apressure indicator 27 for gauging discharge pressure; discharge hoseconnector 12; and optional discharge valve 10 for manually controlleddispensing of compressed air. Discharge hose 4 is a flexible tubeconnected to discharge hose connector 12. Discharge hose 4 is used fordispensing compressed air from within tank 1, and can be configured as astatic shape, coiled, or combined with an optional self-retracting hosereel 23 as shown in FIG. 5.

[0021] An electrical trigger device 16, FIG. 4, is provided anddetermines when there is enough electrical charge (energy) stored incapacitor 15 as an electrical power storage device to energize solenoid8. Capacitor 15 will be of low cost and small size, generally in the2200 micro Farad size range. The trigger device 16 in its essentialembodiment includes a diode 16 a and transistor 16 b arranged as shownin FIG. 4A that function together to detect a fully charged capacitor15, distribute this stored energy to solenoid 8, and then reset thecircuit so that the energy supplied by photovoltaic cell(s) 14 canrecharge capacitor 15 to repeat the cycle. The capacitor 15 triggerdevice 16 and other electrical components are mounted on a circuit boardB located inside the tank 1, FIG. 2. The circuit board is fastened by aU-shaped bracket to the solenoid housing as shown in FIG. 3. If it isdesired to give an indication external of the tank 1 that the solenoid 8is energized, LED 17 can be optionally installed in the circuit as shownin FIG. 4. A current limiting device 18, which may comprise a resistor,may be required in the circuit dependent on the current handlingcharacteristics of photovoltaic cell(s) 14.

[0022] The air supply device also may contain the following optionalfeatures: (a) a pressure switch 28 to shunt excess electrical potentialfrom photovoltaic cell(s) 14 to the charging of a rechargeableflashlight 22, FIG. 5, that is disposed on, and preferably builtintegral to the carry handle 21 such that the flashlight body functionsas the carry handle for tank 1; (b) an AC/DC or DC/DC power adapter 29for powering the air supply device from an external electrical source;(c) a C-shaped (or other shaped) strap connector 24, FIG. 6, which isfastened on the air reservoir tank 1 and which receives and is lockableonto an elongated male bracket 25 attached to a truck bed, FIG. 6 (orother structure) when the air supply device is positioned on the truckbed proximate the front wall thereof so as to prevent the theft of thedevice, the bracket 25 having a punched or otherwise-formed hole toreceive a common padlock in a manner that also passes through the strapconnector 24 to lock the connector and the bracket together; (d) airdispensing valve 10 movable relative to valve seat 10 a and configuredas a manually depressed button, or activated by a lever 30 disposed on acarrying handle 21 attached to tank 1, FIG. 7, such that when the lever30 is manually squeezed, the lever rocks on pivot pin 31 in a manner todepress air dispensing valve 10, which than opens relative to seat 10 aand supplies compressed air to the discharge hose 4; and (e) a pressuregauge 26, FIG. 5, for indicating tank air pressure. In an alternativeembodiment of the invention, the discharge hose connector 12 can beomitted and replaced with hard piping so that the air supply device canbe used as an integral power supply subcomponent to a larger system. Theair reservoir tank 1 may or may not require customizing to conformwithin the encompassing larger system and may or may not require theremote location of the photovoltaic cells 14 as a power source. Stillfurther, the solenoid pump assembly 19 alternatively may be mounted ordisposed externally to an air reservoir tank 1 as either a retrofit toan existing passive air tank, or as an alternative way to construct anair supply device pursuant to another embodiment of the invention.

[0023] In operation, photovoltaic cell(s) 14 produce electric currentthrough exposure to any incident light energy. The electric charge isstored in capacitor 15. Once capacitor 15 achieves a charge sufficientenough to overcome the breakdown voltage of the trigger device 16, theelectrical charge is then free to pass through to the coil of solenoid8, FIG. 4, to power the solenoid. An energized solenoid 8 creates anelectromagnetic flux passing through the center of the solenoid 8.Plunger 7, which is located in the center of solenoid 8, resists theelectromagnetic flux, which causes plunger 7 to thrust rapidly upwardsout of solenoid 8. The air on the leading surface of plunger 7 iscompressed through check valve 13 and into the air reservoir tank 1. Thecharge in the capacitor is diminished rapidly and plunger 7 self centersback into solenoid 8 as the flux relaxes. Gravity helps the plunger 7retract into the solenoid coil in vertical plunger orientations as shownin FIG. 3. In other plunger orientations or to speed up retraction ofthe plunger 7, a retract spring 32 optionally may be provided as shownin FIG. 3 to bias the plunger to this end. Additional plunger retractionspeed can be achieved by modifying the trigger device 16 to not justrelax the current flow in solenoid 8, but to reverse the current flow tothereby forcibly retract the plunger 7 within the solenoid 8. Thewithdrawal of plunger 7 creates a slight low-pressure area within thecavity of valve manifold 11. This vacuum is relieved by atmospheric airpressure overcoming the valve stem seating pressure in Schrader styletank valve 3 and enters the valve manifold 11 internal cavity. The airsupply device is now ready for another cycle. The frequency of cycleswill depend on available light, but will most likely not exceed 2 cyclesper second at maximum sunlight due to the duty cycle limitations of mostcommonly commercially available solenoids.

[0024] Once the air reservoir tank 1 is at the maximum designedpressure, the backpressure from the compressed air will counterbalancethe thrust force of plunger 7, and the plunger 7 will no longer be ableto further compress air into the tank. Plunger 7 will be stalled, withcapacitor 15 continuing to dissipate energy into solenoid 8. This “selfmaintaining” mode can be held indefinitely until gradual leakage reducesair volume to the point where the plunger 7 can move forward and replacethe escaped air. Alternatively, a pressure switch 28 can detect a fulltank of air, and disconnect the solenoid driving circuit shown in FIG.4. The pressure switch 28 can then optionally redirect the electricpotential to charging a flashlight 22, which would be beneficial fornighttime use of the invention. The flashlight 22 may be built into thecarry handle 21 of tank 1 so as to prevent loss/theft of the light. Theflashlight 22 will shine across and illuminate the pressure indicator 27at gauge port 5 as well as illuminate whatever equipment is receivingthe compressed air being dispensed from the air supply device.

[0025] Although certain illustrative embodiments of the invention havebeen described herein, those skilled in the art will appreciate that theinvention is not limited thereto and that changes, modifications and thelike can be made thereto without departing from the spirit and scope ofthe invention as set forth in the appended claims.

I claim:
 1. A self replenishing, portable air supply device, comprisingan air reservoir tank, one or more photovoltaic cells exterior of theair reservoir tank, a capacitor for receiving electrical power from theone or more photovoltaic cells and intermittently discharging to asolenoid, said solenoid then mechanically compressing air into the airreservoir tank.
 2. Air supply device of claim 1 wherein the capacitorand solenoid are disposed inside the air reservoir tank.
 3. Air supplydevice of claim 1 including a flashlight disposed on the air reservoirtank.
 4. Air supply device of claim 1 including a self-retracting hosereel disposed on the air reservoir tank.
 5. Air supply device of claim 1including a hose pressure indicating gauge with pressure readoutdisposed on the air reservoir tank.
 6. Air supply device of claim 1including a manually activated valve disposed on the air reservoir tankto dispense compressed air.
 7. Air supply device of claim 1 including aconnector to secure the air reservoir tank in a location of use.
 8. Airsupply device of claim 7 wherein the connector secures the air supplydevice on a pick-up truck bed.
 9. Air supply device of claim 1 includinga one or more photovoltaic cells for location remote from the airreservoir tank.
 10. A self replenishing, portable air supply device,comprising an air reservoir tank and one or more photovoltaic cellsexterior of the air reservoir tank to power an air compressor pump whichresides inside the tank.
 11. A self replenishing, portable air supplydevice, comprising an air reservoir tank, one or more photovoltaic cellsexterior of the air reservoir tank to provide electrical power to apower storage device, which intermittently provides electrical power toan air compressor pump.
 12. The air supply device of claim 11 whereinthe air compressor pump receives atmospheric air to be compressed via acheck valve on the tank.
 13. A method of supplying compressed air,comprising generating photovoltaic electrical power using light exteriorof an air reservoir tank, storing the electrical power, andintermittently providing the stored power to an air compressor pump topressurize the air reservoir tank.
 14. The method of claim 12 includingintermittently providing the stored power to an air compressor pumpinside the air reservoir tank.
 15. An air reservoir tank having amanually activated air dispensing valve.
 16. The tank of claim 15wherein the air dispensing valve is a pushbutton or a pivotable leverthat engages the pushbutton.
 17. An air reservoir tank having aflashlight thereon.
 18. The tank of claim 17 wherein the flashlightprovides a carry handle for the tank.
 19. The tank of claim 17 includinga photovoltaic cell to supply electrical power to charge the flashlight.20. An air reservoir tank having an air dispensing hose disposed on areel that retracts the hose when it is not in use.
 21. An air reservoirtank having an air pressure gauge to display air discharge pressure inthe hose.
 22. An air reservoir tank having a connector by which the tankcan be held in position.